Washington D.C. [USA], Apr 26 (ANI): North Korea had slapped the United States with a USD two million medical bill for Otto Warmbier, an American school student held captive by Pyongyang in 2016 according to the latest report.

North Korea further insisted that the U.S. sign a pledge to pay the bill before releasing Warmbier a year later, The Washington Post, reported on Thursday quoting sources familiar with the matter.

Warmbier, who travelled to North Korea as a part of his college trip, was released from custody in 2017 in a vegetative state and died just six days after he returned home to the U.S.

Sources said that the bill was given to former State Department Special Representative for North Korea, Joseph Yun, who had orders from President Donald Trump to bring Warmbier home.

Yun had signed the bill after informing then-Secretary of State Rex Tillerson about it, the source added.

However, Yun has denied confirming such reports.

"I cannot confirm that," Yun told CNN.

"These are diplomatic exchanges and negotiations that I do not confirm," he added.

The bill went to the Treasury Department, where it remained unpaid throughout 2017, sources said. However, it is unclear whether the Trump administration later paid the bill, or whether it came up during preparations for Trump's two summits with North Korean leader Kim Jong Un.

Meanwhile, the White House has also declined to comment on the issue.

"We do not comment on hostage negotiations, which is why they have been so successful during this administration," White House Press Secretary Sarah Sanders was quoted as saying.

Another source told CNN that the U.S. has not paid the bill and has made it clear to North Korea that it has no intention to ever pay it.

After the second summit with the North Korean leader in Vietnam in February, Trump said that he does not hold Kim responsible for Warmbier's death.

Otto suffered severe brain damage during his captivity. The Trump administration placed intense pressure on Pyongyang to release Warmbier when they learned of his condition. (ANI)